Moving A Database

I have two computers, both with SQL Express 2005 and SQL Server Management Studio Express. I created a database on one computer, and need to copy it to the other computer. I'd like to do it all through the Management Studio interface, without using SQL commands, since I only need to do this manually.

I detached the two files, copied them to the second computer, and tried to attach them. This is generating lots of messages about not having the necessary permissions of various sorts. I think the main problem is that I don't know how to set up the database's users in a way that allows the second computer to attach the database.

I've tried Windows authentication, using a Windows user that has the same name and password on both computers, and I've defined that Windows user as a user within the database. I've connected to SQL when logged in as that user.
I've tried SQL authentication also, defining the same SQL user within both SQL Servers, as db_owner. But when I try to attach the database, I see no place to specify the user that I intend it to use, and it still fails. If I connect to SQL as that user, then SQL doesn't have permission to look at the file system to find the MDF file.

I'd appreciate the help in learning how to do this with both Windows authentication and SQL authentication, via the Management Studio's GUI. Most of the documentation I've seen covers how to do it by using SQL language commands, and I'd like to avoid that.